The conventional third input means of a computer mouse generally provides page-up and page-down functions. The third input means generally comprises a grating wheel, a light source, and a photo-receiver arranged on a circuit board placed outside the grating wheel. The signal received by the photo-receiver will be influenced by the rotating grating wheel and then trigger an internal circuit controlling the mouse's page-up and page-down functions.
However, in the above arrangement, the accuracy of the signal for page-down or page-up functions is sensitive to the relative positions of the grating wheel, light source and receiver. The third input means of the mouse will malfunction if those optical elements are not carefully set up.
Moreover, those optical elements are soldered to the circuit board, thus causing manufacturing problems and higher costs.
The present invention provides a reliable multifunction input module having a clamping stage, a clamping groove on the clamping stage to clamp a light source and photo-receiver, and a rack for pivotally arranging an optical chopper. By the inventive module, the chopper, light source, and photo-detector can be easily and firmly assembled to the circuit board with the help of the clamping stage and the clamping hooks formed on the clamping stage.